Sound reproducing device



Sept 20, 1932 B. J. cHRoMY 1,878,232

SOUND REPRODUCING DEVICE Filed Sept. 17. 1928 Y, si? v /4 Patented Sept. 26, 1932 r 'n Wazaa Preis BEN zr. cHEoivrY, or HorKrNs, MrNNEsorA, AssreNoE To Winni) EAnro, iNe., or NEW YORK, N. Y., A ooraroEATroN or. DELAWARE Y soUND EEEEonUoiNG DEVICE Application filed September 1'7a 1928. Serial No. 306,540.

This invention relates to radiov signaling systems generallyjand more specifically to soimd reproducers. An object of this invention is to provide a device'for the reproduction of radio signals which will not be abnormally actuated by signals of greater than normal intensity.

Another object of this invention isto providea loud speaker forV radiosignal reproduction Which Will respond only iny normal intensity to signals of vgreater than normal V plished by providing a device Within the loud v -Referring moreuspecifically to Figi speaker or soundV reproducing mechanism for governingthedensity of the magnetic uX passing through kor around the sound prof ducing diaphragm or the diaphragm actuating armature. This uX density governing device may be adjusted to operate only wheny the electrical energy coming'to the soundvreproducing device from the signal ampli-fier is of such intensity -as to produce distortion commonly calledfblasting in the reproducing device.v l

' ln the accompanying drawing Fig. l isa vertical sectional vievv of av sound reproducing device embodying this invention. Fig. 2 is a vertical cross sectional vievv of a magnetic diaphragm type of loud speaker unit embodying this invention. Fig. 3 illustrates asound reproducing device in which this Yinvention isincorporated is connected'to an audion amplier. Fig.. 4 illustrates another schematic diagram of connections Whichvmay be Aused in this invention.l Fig. 5 Vshows `a fragmentarycrosssectionalvievv of a further modiiication of this invention.l

oftheY Ydrawing the reference character vl designates a large loud speaker diaphragm commonly referred to as the cone type of diaphragm. The diaphragmactuating rod isv designated hy the character 2. lhe actuating rod is connected to Vthe armature or movable coil 5 by the members 3 Which engage the circumferV ence/of the coil. The armature movesin ai small piece of magnetic material 7 may be disposed Within thecoil to reduce thereluctance of the air gap. "A highly resilient mem= bei 9 preferably of magnetic materialfis at?` tached to the magnet -6 adjacent to the air gap Within Which the coil 5 is disposed. The screw Sfsupports the member 9;V A bar 9', also of magnetic material is attached tothe member 9. i A coil'lO is mounted upon thel bar 9,7. rThe coil l0 Vmay be connected either in series or in parallel With the coil to the output circuit ofal signal amplifier. vVlhensignal energy. ofgreater. than normal intensity isfed to the sound reproducing mechanism the bar 9 isl caused to move closer -to thev air gap ofk themagnet 4by virtue of the mag-` netic iiux set upin this bar through the action 'of thecurrent in thev coil l0 and the flux density in the air gap is decreased thereby reduc# 'ing the intensity of the sound reproduced to normal. The bar 9 may be'madeofa-n alloy of cobalt and iron andmay be magnetized into a permanent magnet. r 1 A A modification of this invention arv magnetic diaphragm is used for theproductionof soundvvaves is shown in Fig. 2; lnthis figure,2l designates the diaphragm lof magnetic material. The periphery of the diaphragmis mounted between the cap and the housing 22. .The bottom 22a of the sound reproducer housing 22 is attached to the side Walls of the housing by screvvsr 30.V rlhe housing may `be. made ofv phenol condensation products, hard rubber or similar insulating products..v Other materials possessing very feeble magnetic properties may also be used. A L n Afframe 23' which maybe made of soft iron or other metallic materials I possessing magneticfproperties, isY provided With poleV pieces 23'51These Apole pieces 'extend upwherein.

wardly to close proXimity of the diaphragm 21. The frame 23 is held within the casing 22 by screws 28 which extend through the bottom 22a. A coil 29, such as is employed in radio telephone head sets and loud speakers is :mounted upon the frame 23. .This coil is connected to the output of a radio signal ampliiier or other signal amplifying system. The current flowing through this coil 29 magnetizes the frame 23 in Yaccordance with theV modulated signal energy. The diaphragm 21 is thus caused to vibrate in accordance with the modulated signal energy.V

A movable bar 24H2 ofA materialfhaving a high magnetic permeability, such as soft iron vor certainspecial -alloys of nickel and iron `is mounted upon the Aframe l23 adjacent to the pole pieces by meansv of a spring strip 24a. A coil 25 having a 'large number of turns of relatively line wire, such assis used in winding telephone receiver coils of high impedance, Ais mounted upon the bar 24?).

This small coil'may be connected either in parallel or in series with the coil 29 to the output oi' a signal amplifier.`

In'Fig. 3 is shown a manner in which the device comprising thi-sinvention may be Sli connected to a signal amplier. ln this iigure, :15 indicates an amplifying thermionic vacuumtube or audion.` rlhe'audion anode source of supply 14 is Aconnected throughvthe impedance 13l to the .plate electrode.' The volume or sound intensity governing coil and the diaphragm actuating coil of the sound reproducer are connected in parallel with each other to the output of theaudion 15.

,j In Fig. l is shown another manner in which the device disclosed in this application may be connected to a'signal amplifier. The coils 5 and 10 of the sound reproducer' are con-A nected in series to the output of the audion 15.

VThe modified form of this invention shown inV Fig. 2`may be connected to the output circuit `of fa signal amplifier 15 in any one of the ways shown in Fig. 3 andF ig. 1, that is the coil; 25'V may be 'connected either in series or in parallel with the coil 29 to the output circuit of the audion 15,

In Fi'gp the armature coil 5a for actuat# ing the acoustic diaphragm of ailoudspealrer through the varms 3a is mounted `betweenthe pole pieces cfa permanent magnet 6a. `The magnetic `iiuir deecting bar is supported against the magnet 6a by a` resilient member r 9a and screw 8a.

Screws 32 and 31 are provided through the pole pieces of the magnet Coil springs 33' and 311 are provided to furnish adjustable tensionagainst the bar 35. The force exerted by the springs 33 and 34 against the bar 35 may be. varied by adj ustingthe screws 32 and 31 respective ly. The intensity of the received signals at which the bar 35'will be caused to move closer to the polefpi'e'ces and deii'ecta greater percentage of the magnetic iiuX from the air gap of the magnet 6a may thus be varied by adjusting either one or both of the screws 31 and 32.

movable electromagnetic means 'adjacent said iirst named means for automatically governing the intensity of the sound reproduced.

2.` In a'sound reproducingdevice the combinationwitha signal ampliiier of a diaphragm, electromagnetic.` means connected to the output o'fsaid signall amplifierV for actuating the said diaphragm in accordance with signal energy fed into said meansfirom the said amplilier, and 'electrorr'iagnetic meansor governing the t intensity .of the reproduced sound V-:v..tves, said last inentioned velectromagnetic means being energized by energy Vfrom Vsaid ampl'iiierv. i

. 3. Ina sound reproducing ydevice the com;V bination of a diaphragm, ele'ctrodyn'amic means Afor actuating the said*v 'diaphragm` in accordance with voice vmodulated relectrical sov energy, a barof magnetiem'aterial adjacent tosaid electrodynamic means` for deflecting a certain .part of the magnetic flux normally passing through said electrodynamic means, and a coil' mounted upon the said bar, said coil being connected together with the said electrodynamic means to the output of a signal amplifier so that the magnitude Vof the current flow-ing throughthe ysaid coil governs thexdis'placement between the 'said bar and the electrodynamic means. v l

4. In a. sou-nd reproducingl device the combination of aV diaphragm, electrodynamic meansfor actuating the saidV diaphragm in accordance with voice modulated-electrical energy, a resilientmember, a barfof mag@ netic material supported adjacent to said electrodynamic means by the said resilient member for deflecting a certain part of the magnetic iuX normally passing through the saidelectrodynamicmeans, andacoil mounted Vupon the said bansaid coil beingconnected together with the said-electrodynamic means to the output circuit of a signal amplifier so that the magnitude ot' the currentlowing through the said coil governs the displace-` interacts with said iuctuating magnetic eld through the action of another of said windings.

6. In sound reproducing devices the com-A 6 bination of a diaphragm, electromagnetic means for actuating said diaphragm and separate electromagnetic means operated inV accordance with energy impressed upon said first mentioned electromagnetic means for' 10 governing the intensity of the sound produced. Y

7. In a sound reproducing device the coma bination of a diaphragm, electromagnetic means for actuating said diaphragm in accordance With modulated electrical energy, a normally high reluctance magnetic shunt ,around said electromagnetic means, and electromagnetic means for controlling the reluctance of said normally high reductance magnetic shunt around said first mentioned electromagnetic means. Y

In testimony whereof I aiix my signature.

BEN J. CHROMY. 

